Remove Scope::scope_uses_this_ flag

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 8184bd8d5f5af2bc93a872c80c71ab3b7cce8001..543f82ee56a281dfc5984a7aa9a9be91319cf659 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -2215,7 +2215,6 @@ ParserBase<Traits>::ParsePrimaryExpression(ExpressionClassifier* classifier,
           break;
         }
       }
-      scope_->RecordThisUsage();

[arv (Not doing code reviews), 2015/05/06 14:23:52]

It is not clear to me how this works now? Don't we use this information to
determine if we should introduce a binding for this? Maybe we always introduce a
this binding now (-arrows and eval)?

[wingo, 2015/05/06 14:37:42]

ThisExpression for the full parser will create an unresolved VariableProxy which
in Scope::Analyze() will be plugged to a Variable.  When that happens the
Variable itself, wherever it is declared, will be marked as used.  The variable
will also be marked as used if there is a nested direct eval(), though perhaps
those conditions are too conservative (see Scope::MustAllocate()).  Anyway, with
all of that, the flag is redundant.

       result = this->ThisExpression(scope_, factory(), beg_pos);
       break;
     }
@@ -3241,7 +3240,6 @@ ParserBase<Traits>::ParseStrongInitializationExpression(
   Consume(Token::THIS);
   int pos = position();
   function_state_->set_this_location(scanner()->location());
-  scope_->RecordThisUsage();
   ExpressionT this_expr = this->ThisExpression(scope_, factory(), pos);
 
   ExpressionT left = this->EmptyExpression();